3.5" floppy drive in IBM XT?

From: Joe <rigdonj_at_cfl.rr.com>
Date: Tue Apr 8 20:13:00 2003

   Thanks for the info but I don't see the pads that you're talking about. Near the center of the card are pads for a 14 pin DIP with nothing strapped. It's unlabeled but is located between ICs 8D and 10D. Right next to the bracket on the very end of the card is a place for an 8 pin DIP. It has the package outline painted on the board. But it has two rows on header pins installed instead of a DIP package. (The rows are .4" apart.) One row of pins is marked S1 and the other is marked 1, 2, 3, 4. There's nothing jumpered on it either but I suspect that it's used to select the drive sizes.


At 02:49 PM 4/8/03 -0700, you wrote:
>On Tue, 8 Apr 2003, Joe wrote:
>> The controller is full length and has XEBEC chips and a Z-80 CPU.
>> I'm sure that it's MFM. It's marked IBM and next to that is a paper
>> sticker that says #1501492. Also marked IBM 6135984 in copper foil. My
>> diagnostic tool shows four settings in the ROM, the 10Mb drive is
>> third setting. I didn't look at the capacity of the other settings.
>> It's running this drive as a 10 Mb MFM drive but the drive is rated as
>> a 32Mb RLL capable drive.
>> my controller is an original IBM 10 Mb MFM HD controller. It's only
>> using 10 Mb of the drive.
>Near the middle of the board are 8 solder pads. By jumpering those (they
>are the right size for a 4 position dip switch), you can get the
>controller to use the other setting that are in its ROM. The 4 positions
>are 2 for each drive, resulting in 4 possible combinations for each
>drive. 10M, the default, is both switches open.
>OR, there are software ways tio override the controller -
>check with Steve Thatcher.
Received on Tue Apr 08 2003 - 20:13:00 BST

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